[GRASS-user] TopoFlow and GRASS (or any continuous distributed hydrologic model)

[M S]

r.gwflow can help with the groundwater flow.

The r.watershed module can help with where streams in basins originate
and go to the outlet.  The add-on of r.stream.extract can use
weighting parameters to adjust where the streams start (eg. increase
accumulation in wet areas, decrease accumulation in dry, and
montgomery's exponent for adjusting accumulation thresholds to have
more streams in steep areas or flat areas).

These modules will help illustrate where streams begin based on
contributing area/accumulation.  The USGS gauging stations are a good
way to validate your model.

For long term, or rain-fall event orientated analysis, r.water.sim
seems applicable.  It will output depths and discharge rates based on
rainfall and other input parameters.  Validating these simulation
results seems reasonable if you have real time data for a given rain
event with corresponding discharge rates or depths at stations in the
watershed of interest.

I have not looked at the HydroFOSS as an addon, but it indicates it
factors in evapotranspiration.
http://www.foss4g2006.org/contributionDisplay.py?contribId=157&sessionId=40&confId=1

Good luck and please post back any updates.

Mark

On Wed, Apr 28, 2010 at 11:28 AM, stephen sefick <ssefick at gmail.com> wrote:
> I would like to be able to model groundwater and surface water flow
> for some particular watersheds with usgs gauging stations.  The
> gauging stations are to help parameterize/validate the modeled
> discharge.  I would then like to be able to try and predict
> probability of intermittance, or, in other words, where permenant flow
> starts in the watersheds under investigation.  I think that D8 flow
> algorithm based distributed hydrologic models are the way to do this.
> If I am wrong I would greatly appreciate this being pointed out.  I
> was wondering if there were any implementations for long-term
> simulation (I would like to account for different water years).  Also,
> I would like to, at the least, use GRASS as a preprocessor for gridded
> rainfall and Evapotranspiration time series (along with whatever else
> may be necessary input data).  I have looked into GSSHA, but don't not
> have the resources for acquiring the WMS software needed to drive the
> model ($1500), and it looks like TopoFlow for the Colorado CSMDS
> modelling group would work.  If there are any suggestions, comments,
> or criticisms of my decisions for trying to attack this problem please
> point them out.  Thank you all very much for your wonderful help.
> kindest regards,
>
> Stephen Sefick
>
> On Thu, Apr 22, 2010 at 8:54 AM, Rich Shepard <rshepard at appl-ecosys.com> wrote:
>> On Thu, 22 Apr 2010, stephen sefick wrote:
>>
>>> I would like to simulate the hydrology of a watershed.  Does anyone have
>>> guidance for this particular endeavor- especially with the help of GRASS
>>> GIS as a raster processor, or engine for model analysis?
>>
>>  There are several hydrologic modules available for your use. The raster
>> manual (r.*) has details on each, and the wiki has a section on hydrological
>> modeling.
>>
>>  The question you need to answer in order to get more focused help here is
>> just what it is you want to do. What problem are you trying to solve? What
>> behavior(s) do you want to explore? Specificity, and telling us what you've
>> done so far to educate yourself, goes a long way to helping you.
>>
>> Rich
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>
>
>
> --
> Stephen Sefick
>
> Let's not spend our time and resources thinking about things that are
> so little or so large that all they really do for us is puff us up and
> make us feel like gods.  We are mammals, and have not exhausted the
> annoying little problems of being mammals.
>
>                                                                -K. Mullis
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